    [Patent document 1] JP-2007-517553 T (US20070032733 A1)
The term restless legs syndrome (referred to as RLS) was created by neurologist Ekbom of Sweden in 1945. RLS is a neurological disease classified into a dyskinesia and has been an issue as a modern disease at home and abroad since the 21st century.
In Japan, RLS is called “muzu-muzu (signifying creepy) legs syndrome.” RLS provides an unpleasant feeling centering on a leg, which is accompanied by an unpleasant and intolerable dysesthesia/paresthesia (crawly/creepy/aching) in a leg. The impulse (i.e., desire) of wanting to move a leg becomes strong at night, thereby causing insomnia. RLS is thus classified into a somnipathy or sleep disorder.
The unpleasant feeling of the leg can be relieved by moving or massaging the leg. In contrast, if being left still as it is, the unpleasant feeling worsens as the night progresses. The RLS patients in Japan are inferred to be about 4,700,000 people, which is 2 to 5% of the population. The prevalence rate of RLS rises with aging, thus exhibiting the peak at 60 to 70 years old. The male-female ratio is 1:1.5. The prevalence rate of RLS is inferred to increase in the near future as society ages.
Further, 80% of RLS patients are accompanied by periodic limb movements during sleep (referred to as PLMS or PLM during sleep), whereas 20% are not accompanied by PLMS. Therefore, the RLS diagnosis at the present time is largely dependent on the complaint centering on the sense of discomfort. For example, there is a technology (refer to Patent document 1) which detects a breathing disorder during sleep. In contrast, there is no objective and quantitative diagnostic method of RLS presently.
As explained above, PLM during sleep at night is observed in about 80% of RLS.
The all-night sleep polygraph inspection (polysomnography: PSG) is thus considered to be indispensable for diagnosis of RLS. The PSG inspection detects periodic stress (i.e., periodic limb movements: PLM) of muscles which appears in an electromyograph attached to a leg, thereby detecting RLS.
However, RLS is a condition mainly produced during sleep. Until the condition of a disease advances to some extent to thereby reach a level where the restless sense is recognized, any petition (complaint) is not obtained from a person himself/herself. In addition, when there are no self-defined symptoms, no one notices that RLS causes a sleep disorder (sleepiness). Therefore, a motivation to undergo the PSG inspection is not produced. Thus, early diagnosis is not easily achieved.
Furthermore, the PSG inspection requires a surveillance monitoring requiring one night of admission to a hospital, and obtains no diagnosis with respect to the RLS patient having no PLMS, thus possibly resulting in useless inspection.
That is, about 20% of RLS patients do not exhibit PLMS. Even if having the restless sense in the legs, the legs of those people do not actually move periodically. Thus, even if those people undergo the PSG inspection, RLS of those people cannot be detected. Therefore, under the present circumstances, the confirmation of the effect of medical treatment such as using medicine depends on the subjectivity of the person himself/herself.
In addition, the prevalence rate of RLS is 2 to 5% of a population, which is considered to be significantly great, thereby making it very difficult to execute the PSG inspection for all the diseased people. Such a circumstance requires a development of new techniques such as an inspection apparatus to detect dysesthesia/paresthesia of the leg in determination items other than PLMS while allowing medical practitioners to objectively evaluate curative effects, and a new home simple monitor to use PLMS for screening.